D
ETERMINE THE
S
AMPLE
M
ASS
Sample Data Worksheet for Gas Adsorption on page B - 1
The equipment images in this topic may differ slightly from your equipment; however,
the instructions are the same unless otherwise noted.
Clean, dry sample tubes are essential for accurate results. How much sample to use can be
determined best by experiment. In general, a sample providing 40 to 120 square meters of total
surface area is recommended for nitrogen analysis. Less than 40 square meters may cause
unreliable results. More than 120 square meters will extend analysis time.
Smaller quantities are required for samples having high surface areas. These samples require
careful weighing after degassing because a small error may represent a considerable percent of
total weight. Proper weighing techniques are most important in this case. Use no less than 100 mg
to reduce the effect of weighing errors.
Care should be taken when loading powders: the accessory funnel is useful for this purpose.
Large granules or chunks may be loaded with forceps.
Analysis results are expressed in units of surface area per gram of sample; therefore, it is
important to know the true sample mass.
Follow the instructions on the
Sample Data Worksheet
and complete all fields to find the true
sample mass.
1. Record the sample tube identification on the
Sample Data Worksheet.
2. Place the sample weighing support on the balance. Tare the balance and allow it to stabilize
at zero (0).
3. Place the empty sample tube set (empty sample tube and stopper) on the sample weighing
support and place it on the balance.
4. Record the stabilized mass on the
Sample Data Worksheet
. Remove the sample tube set
from the balance.
Do not touch the sample with bare hands while performing the following steps. Doing
so could affect the accuracy of results.
5. Place a sample container on the balance. Tare the balance and allow it to stabilize to zero.
6. Slowly pour the specified amount of sample into the sample container.
7. Remove either the rubber stopper from the sample tube.
8. Use the sample tube funnel (provided in the accessories kit) and pour the sample from the
weighing container into the sample tube.
Determine the Sample Mass
VacPrep Operator Manual
061-42802-01 (Rev B) — Apr 2021
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